The main thrust of the laboratory is focused on the molecular mechanism of platelet aggregation, including both hemostasis and thrombosis, investigating the influence of pressure on the hydration layer surrounding the electrically charged amino acid residues involved in platelet aggregation. We have been investigating the molecular mechanism of platelet interactions in DIPA (decompression-inducible platelet aggregation) for the past several years. We have found that the oppositely charged amino acid residues, i.e., positively charged arginyl and negatively charged aspartyl residues interact with their respective receptor sites. Last year we observed vascular occlusion in the small blood vessels in the web of the frog;s foot and in the ear of the mouse. During the current year we have found that the volume of human PRP is increased by 0.03% or 3 ml per liter of packed thrombocyte volume when platelet aggregation is induced by decompression. A similar increase in the volume of human PRP is now being observed when platelet aggregation is induced by the agonists, epinephrine (adrenalin) and ADP. We theorize that compactly organized water molecules, when randomized into the bulk phase, acquire thermal motion which causes a temperature drop; and that human platelet aggregation is a entropy driven process similar to human red cell sickling. To confirm our hypothesis, we are utilizing a newly designed dilatometer which has a "built-in" thermistor, to measure eh volume increase and temperature drop when platelet aggregation is induced by epinephrine (adrenalin) and ADP.